1.) In the laboratory, a skeletal muscle is extracted from an animal and placed
ID: 3524384 • Letter: 1
Question
1.) In the laboratory, a skeletal muscle is extracted from an animal and placed in a solution that contains no calcium ions.
a.) Will the isolated muscle in this condition contract when it is externally depolarized (stimulated)? (1 point)
b.) Explain your reasoning with the physiology you have learned (include specific mechanisms) (at least four correct key aspects to the mechanisms involved needs to be included for full credit (3 points).
c.) If this muscle cell were a contractile cardiomyocyte instead, would your answer change, if so why, if not, why? 1 point
2.) You then add a neuron to the solution that synapses on the muscle.
a.) Will the isolated muscle contract when the added nerve is stimulated? (1 point)
b.) Explain your reasoning with the physiology you have learned (include mechanisms). At least four correct aspects to the mechanisms involved must be included for credit (3 point per)
c.) What type of neuron is synapsing on the skeletal muscle? (1 point)
Petri Dish No Calcium Stimulus Skeletal muscle cellExplanation / Answer
1)a) Even if the solution that muscle is kept in is calcium fee, the skeletal muscle has calcium storesd in the cells in the sarcoplasmic reticulum.
So the effect of depolarization would be that, there will be contraction , which will be slow one , and will reach to the peak very slowly and will be very weak.
b)The reason that there still will be contraction is that the depolarization will lead to the release of the calcium from the sarcoplasmic reticulum, which will bind to the actin filaments, activates them , which in turn binds to the myosin which finally causes the contraction of the skeletal muscle.
The contraction will be slow due to the low calcium concentration on the membrane.
c) In the place of skeletal muscle , if an cardiac muscle is placed , there will be no contractions.
This is because the sarcoplasmic reticulum of the cardiac muscle isnt dveloped as much as of skeletl muscle, so it depends mainly on the extracellular calcium for the contraction to occur.
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